use your loaf

use (one's) loaf

slang To think logically, rationally, or with common sense; to use one's head. The phrase comes from rhyming slang in which "loaf" is short for "loaf of bread," which rhymes with "head." Primarily heard in UK, Australia. Come on, Dean, I know you can figure this out on your own. Use your loaf! Jenny finally remembered to bring the right books home to do her homework. I'm glad she's finally using her loaf.
See also: loaf, use
Farlex Dictionary of Idioms.

use your loaf

use your common sense. British informal
This expression probably comes from loaf of bread , rhyming slang for ‘head’.
See also: loaf, use
Farlex Partner Idioms Dictionary
See also:
  • use (one's) loaf
  • loaves
  • loaf of bread
  • iron poof
  • I should cocoa
  • I should cocoa!
  • cocoa
  • be on (one's) pat
  • have a Captain Cook
  • ginger beer
References in periodicals archive
And how often have we been told to "use your loaf"?
Book uses its loaf to find origins of words
USE YOUR LOAF: Big Issue vendor John with his bread Picture: COLIN LANE
Big Issue team make some extra dough
Campbell Williams, the legal expert attempting to refresh us, said that a good rule of thumb was to "use your loaf".
A look at Barry